Temperature control system



Oct. 1, 1940. .J. M. LARSON TEMPERATURE CQNTROL SYSTEM Filed Feb. 26, 1937 I5 Sheets--Sheet l fl MM a I 1% a m h Wk 6N N. W I a v y m Q a m. Jll w I. m A a m R Z J a m h h k f/ W/ 7 I m I w m H Q m 1 H m N. u u m w Oct. 1, 1940. J. M. LARSON TEMPERATURE coimion SYSTEM 3 Sheets-S heet 2 Filed Feb. 26, 1937 Oct. 1,1940. J M, LARSON 2,216,245

TEMPERATURE CONTROL SYSTEM Filed Feb. 26, 1937 I :s Sheets-Sheet 3 atented Oct. 1, 1940 UNITED STATES PATENT OFFICE TEMPERATURE CONTROL SYSTEM Application February 26, 1937, Serial No. 127,837

16 Claims.

This invention relates to temperature control systems, and more particularly to temperature control systems for regulating temperature in one or more rooms regardless of variations in outdoor temperature or other conditions which might adversely affect the temperature of the room or rooms.

The invention contemplates a system whereby a plurality of rooms may be controlled in such a manner that a uniform temperature may be maintained in all of the rooms or a different temperature may be maintained in each room in accordance with individual rehuirements and regardless of variations in outdoor temperature.

That is, the invention not only contemplates a control system including a plurality of temperature-responsive devices cooperatively functioning to maintain a predetermined temperature in a single room, but also provides a system whereby each of a plurality of rooms may be maintained at a desired predetermined temperature.

A further object of the invention is the provision of a system of temperature control in which variations in one or more remotely positioned w thermostats may vary the effective settingof individual room thermos-tats in accordance with varying requirements, and simultaneously indicate the new setting.

A further object is the provision of a temperature control system of the character described in which a heating system may be provided for winter use and a cooling system for summer use, and in which a temperature-responsive control is associated therewith, whereby either the heating or cooling device may be brought into operation in accordance with seasonal variations in the outdoor temperature registered by one or more outdoor thermostats.

Another object is the provision of a temperature control system having a circulating system adapted for either heating or cooling in accordance with temperature requirements, and in which 'the entire system is controlled over a wide range of outdoor temperatures in accordance with indoor requirements. 3

A further object is the provision of a pneumatic system for variably controlling the heating and cooling mediums in which the pneumatic pressure is controlled by a plurality of thermostats cooperatively functioning under control of diffe nt variable temperature conditions to cause the heating and cooling means automatically to function in accordance with extremely wide temperature range requirements. Also, the variable 5% control is automatically switched from cooling side temperatures prevail, it is desirable to vary to heating, or vice versa, in accordance with requirements, without disturbing the efiectiveness of thevarious control arrangements whereby substantially constant predetermined temperature may be maintained in one or more rooms.

A further object is the provision of a temperature control system of the character described, which will be completely automatic in operation in response to temperature changes and which will be simple in operation, convenient to install, 10 and will not easily get out of order.

Suitable adjustments are provided whereby the temperature-responsive elements, as well as all elements controlled thereby, may function automatically to maintain predetermined tempera- 15 ture in accordance with all normal winter and summer heating and cooling requirements.

It is well known that when extremely high outdoor temperature prevails, it is desirable, in order to prevent physical shock and discomfort in 20 an air cooled room, that the temperature in the room should vary in a predetermined relationship with the variations in the outdoor temperature, that is, it is usually desirable that the room temperature should never be more than from 10 to 25 15 degrees below the outside temperature, and should vary in a predetermined relationship with the outside temperature.

Also, in winter, or when extremely low cutthe setting of the indoor thermostats in a pre- 30 determined relation with the variations in low temperature in order to control the heating medium in a manner to compensate for increased heat loss from cold walls and windows. In some cases there is a considerable difference between the temperature at the room thermostat and the temperature near the walls or at the windows and doors, and automatic variation of the setting of the room thermostat is to compensate for the heat loss due to this diflerence in temperature.

Further objects will be apparent from the specifications and the appended claims:

In the drawings:

Fig. 1 is a diagrammatic view of one embodi- 4E5 ment of the improved temperature control system.

Fig. 2 is a diagrammatic illustration of one of the room thermostats and connections therefor, such as illustrated in Fig. i.

Fig. 3 is a vertical sectional view of one of the room thermostats illustrated in Fig. 1.

Fig. 4 is a transverse sectional view through the base of the thermostat and taken on a line substantially corresponding to line 4-4 of Fig. 3.

Fig. 5 is a fragmentary sectional view illustrating a slightly modified form of room thermostat adapted for use when it is desired to eliminate the outdoor variable control of the setting of the room thermostat.

Fig. 6 is a sectional view through one of the air restriction valves illustrated in Fig. 1.

Fig. 7 is a sectional view of a single thermostat which may be substituted for the series thermostats illustrated in Fig. 1, for controlling the setting of the room thermostats.

Referring to the drawings in detail, a complete installation is illustrated in Fig. 1 including the use of room thermostats I and la. The system is illustrated as installed in connection with the temperature control of only two rooms, A and B. However, it will be understood that any number of rooms may be connected with, and similarly controlled by the system as desired.

In the embodiment illustrated in Fig. 1, each room thermostat, I and la is arranged to control the delivery of either a heating medium or a cooling medium to its respective heat exchanger or radiator 2, to which the heating or cooling medium may be delivered through a suitable conduit 3. Each heat exchanger is controlled by means of a suitable pressure operated valve 4. These valves are preferably of the usual diaphragm or bellows type in which the valve may be closed by air pressure and opened by means of a suitable spring when the air pressure is released.

In the present embodiment a suitable air pressure may be delivered to the radiator control valves from any suitable source through a pressure main 5 and branch conduits 6 and I leading therefrom. The delivery of suitable air pressure to these branch conduits is controlled by means of a four Way valve 8. The valve 8 is movable to two positions, as illustrated by the full lines and dotted lines, and in the full line position shown, the main 5 is arranged to deliver pressure to the branch conduit 6 for so-called summer control; that is, whenever high outdoor temperatures prevail and it is desired to control the inlet of a cooling medium to the radiators 2. When the valve is in this position, the branch conduit I is connected to atmospheric pressure through an exhaust port 9.

When the valve 8 is moved to the dotted line position, either manually or in response to a predetermined low outdoor temperature, the winter control branch conduit 1 will be connected to receive pressure from the pressure main 5 to control the inlet of heating medium to the radiator, and simultaneously the branch conduit 6, or so-called summer control conduit, will be connected to atmospheric pressure through the exhaust port 9. These branch conduits 6 and I are further controlled, by means of the thermostat I, to deliver operating pressure through a conduit l0 leading to the radiator valve 4 from either of the branch conduits 6 or I in accordance with room temperature requirements; that is, during summer, or when high temperatures prevail, the thermostat I may direct pressure from the branch conduit 6 through the valve conduit II) to control the valve 4; and during winter, or low temperatures, the thermostat I may direct pressure from the branch conduit I through the valve conduit II] to control the valve 4.

The room thermostat I is illustrated in detail in Fig. 3, and the conduit connections therefor are illustrated diagrammatically in Fig. 2.

All of the room thermostats may, of course, be

identical in structure and operation if desired, but may be adjusted for efiective operation over different temperature ranges, and all of them may be suitably connected to receive pressure from the branch conduits 6 and I.

The thermostat I illustrated in detail in Fig. 3 and diagrammatically in Fig. 2 may comprise the usual cylindrical temperature-responsive element II, having a push rod I2 associated therewith. The thermostat is provided with a base I3 on which is supported a valve post I4, having a bell crank lever I5 mounted thereon by means of a spring I6, which latter provides a fulcrum for the lever. The base I3 is provided with a small chamber II which provides communication between the winter control branch conduit I and the conduit I8 leading to the radiator valve 4. A restriction valve comprising a screw Fla is threaded into the chamber H for the purpose of restricting the inlet of the branch conduit I. The bell crank lever I5 is arranged to control a vent I8, which latter communicates with the chamber II between the winter conduit I and the radiator valve conduit I0, and it will be apparent that when the vent I8 is completely open the pressure in the conduits 'I and II] will not be suflicient to operate the radiator valve. The thermostat operates to control the vent in response to a predetermined variation in temperature, and the. radiator valve will therefore be controlled in accordance with the variation of room temperature.

The summer control branch conduit 6 communicates with the thermostat chamber Na in the cylinder I I, and when high outdoor temperatures prevail, the four way valve 8 will automatically be positioned as shown to admit pressure into the chamber Ila. The vent I8 will then provide a channel for admitting pressure to the radiator valve controlling conduit I0 in accordance with the setting of the thermostat and variations in room temperature. At this time the branch conduit 'I will be connected to the exhaust port 9 of the four way valve 8. However, as previously stated, this branch conduit I is restricted by a restriction valve I'Ia, and therefore sufficient pressure will be admitted to the valve conduit In to operate the radiator valve 4. When the outdoor temperature reaches a predetermined low degree, the four way valve 8 is automatically moved to the dotted line position for winter control, and the summer control conduit is connected to the exhaust port 9. Pressure may then be admitted to the radiator valve through the conduit I0 and controlled by the vent I8.

In other words, when pressure is directed through the winter control conduit I, the thermostat acts merely to accumulate or vent the pressure directed to the radiator valve and when the pressure is directed through the summer control conduit 6 the thermostat acts as a control valve to direct pressure through the vent I8 to the radiator valve.

The automatic operation of the four way valve 8 is controlled by means of a so-called reverse acting outdoor thermostat I9, which may comprise the usual cylindrical temperature responsive element 20, having a pull rod 2I associated therewith for operating a valve lever 22 to control a vent 23 in accordance with predetermined outdoor temperatures. The pull rod 2I may be pro- .vided with an adjustable nut 24 for varying the effective range of the temperature control of the valve lever 22. The lever 22 is also controlled by means of a spring 25 normally tending to close the vent' 23. The vent 23 is arranged to vent a conduit 26 to which air pressure is supplied from any suitable source through a restriction valve 21.

The conduit 26 communicates with a snap valve device 28 comprising a diaphragm or bellows 29, having downwardly extending spring members 30 thereon. The spring members are arranged to be moved by the contraction and expansion of the bellows 29 and engage a double cone shaped member 3|, which latter forms an extension of a valve 32 for controlling a pressure inlet 33 and an exhaust opening 34 in the valve casing 35. The pressure inlet 33 may be supplied with air pressure from any suitable source and may also be provided with a suitable restriction valve.

The thermostat 19 may be arranged for eifective operation over a comparatively narrow range, preferably not more than 3; for instance from 55 to 52; that is, when the outdoor temperature drops to 55, the thermostat will start to close the vent 23, and when the temperature reaches 52 the vent will be completely closed, and the snap valve 28 will operate to close the exhaust valve 3 1 and admit pressure to a bellows 55 through a conduit 31. The bellows 36 is in turn arranged to operate a lever 38 pivoted at til, and connected to an arm 40 on the valve 5 by means of a link 4|, the parts normally being held in the position illustrated by means of a spring 52. It will therefore be apparent that when the outdoor temperature is at or above 55,

- the vent 25 will be operf and the snap valve 25 will be in the position illustrated, whereby the exhaust port 54 is open and the pressure inlet 55 is closed. The valve 8 will therefore be in the position illustrated to admit pressure to the summer control branch conduit 5 to control the radiator valve 5.

Also, when the outdoor temperature is at or below 52, the vent 23 will be completely closed and pressure will be admitted to the bellows 25 of the snap valve 28 and the exhaust port M will then be closed. The pressure inlet 55 will be open to admit pressure to the bellows 5t and the four way valve 5 will be in the dotted line position and admit pressure to the winter control branch conduit l to control the heat exchanger valve l.

When the four way valve 8 is in the position illustrated in full lines for summer control, it is desirable that a suitable cooling medium should be supplied to the radiators. Also when the four way valve moves to the winter control position, it is desirable to shut off the cooling medium and supply a suitable heating medium instead. This is automatically accomplished by means of suitable pressure controlled valves connected to the summer control branch conduit 5. During summer or when high outdoor temperatures prevail, a supply of suitable cooling; medium is maintained in a container t3, and during the winter a similar supply of heating medium is maintained in a container M. The temperature of the cooling medium in the container 55 may be regulated by means of any suitable refrigerant admitted to suitable coils therein by a pressure controlled valve d5, which valve may be in turn controlled by pressure admitted thereto through a suitable pressure conduit 45, the pressure in the conduit 46 being governed by means of a thermostat ll arranged to open or close a vent ilt in accordance with temperature requirements within the container 43.

The temperature of the heating medium may be controlled in a similar manner by means of a thermostat 49 controlling a vent 50 in a pressure conduit 5| communicating with a valve 52, which latter controls a conduit 53 for governing a suitable heating device in the container 44.

The outlets of the containers 43 and 44 are each connected, as illustrated, to the conduit 3 arranged to deliver either the heating or cooling medium to the radiators in accordance with requirements. Acirculating pump 54 may be provided in the circulating system. A return conduit 55 is connected from the radiators to the inlets of the containers as illustrated.

The outlet conduit of the cooling container is 'provided with a pressure operated valve 56, which is preferably of the so-called reverse type; that is when pressure is applied to a bellows 51, the valve will be open as illustrated, and when the pressure is relieved, the valve will be closed by means of a spring 58. The inlet to the cooling container is provided with a valve 59, which may be similar in all respects to the valve 56. This valve is also provided with a bellows 51a so that it is open when pressure is applied thereto, and will be closed by means of the spring 58a when the pressure .is relieved.

The outlet and inlet conduits of the heating container are provided with valves 60 and (it respectively, which are somewhat similar to valves 55 and 59. However, the valves ti! and iii are of the so-called straight type, whereby when pressure is applied to the bellows 52 and 52a the valves will be closed, and when the pressure is relieved, the valves will be opened by means of springs 53 and 53a. The bellows 57! and 511a and 62 and 62a of the respective valves are all connected to the summer control conduit 5 by means of a suitable pressure conduit M. It will, therefore, be apparent that when high outdoor temperatures prevail, and the valve 5 is in the position illustrated for summer control, pressure will be applied to all of the bellows through the conduit M leading thereto, and the valves 55 and 55 will be open whereby cooling medium may circulate through the radiator system. {it this time, the valves 55 and ti controlling the heating medium will be closed and no heating medium will be admitted. Also when low outdoor temperatures prevail, and the valve 5 is shifted to the dotted line position to apply pressure to the winter control branch conduit l, and connect the branch conduit 5 and conduit M to the exhaust port ll, the pressure in the bellows of the respective valves will be relieved and the valves 55 and till controlling the cooling medium will immediately close, and the valves 55 and ti controlling the heating medium will be opento permit circulation thereof.

As previously stated it is well known, that when extremely high outdoor temperatures prevail, it is desirable in order to prevent physical shock and discomfort in a cooled room, that the temperature in the room should vary in a predetermined relation with the variations in the outdoor temperature; that is, it is usually desirable that the room temperature should never be more than 10 or 15 below the outside temperature, and this approximate relationship should be maintained over a predetermined outdoor temperature range.

An appropriate relationship may be maintained 5 by raising the indoor temperature 1 for every 3 rise in outside temperature above Also when extremely low outside temperatures prevail itis desirable to vary the setting of the indoor thermostat in a-predetermined relation with the till' bil variations in the low temperature in order to compensate for the heat loss from cold walls and windows, or for other reasons.

In order to cause the room thermostats to vary their setting and effectively control temperature relative to variations in high and low outdoor temperatures, a plurality of thermostats 65 and 66 are provided for controlling the air pressure in a conduit 6'! leading to all the room thermostats as illustrated. The conduit 61 is arranged to receive air pressure through a restricted valve 68 from any suitable source. The thermostats 65 and 66 may be substantially identical in structure with the thermostat I9 previously described, the thermostat 65 being straight acting, thermostat 66 being reverse acting; that is, thermostat 65 is arranged to open a vent with a decrease in temperature, while thermostat 66 opens its vent with an increase in temperature.

The thermostats 65 and 66 are adjusted to respond efiectively to difierent temperatures, and thermostat 65 is provided with a substantially air tight chamber 69 with which the conduit 67 communicates through a vent I0. This vent I6 is controlled by a lever II pivoted at 12, and normally pressed outwardly to tend to open the vent III by means of a spring I3. The chamber 69 of the thermostat 65 is connected by means of a conduit 14 to a vent I5 in the thermostat 66. This vent is controlled by means of a lever 16 normally pressed inwardly by a spring 11 in a direction tending to close the vent. Both of these thermostats may be adjusted by means of suitable thumb nuts 18 in the same manner as the thermostat I9.

Referring to Fig. 3, the room thermostats I may be substantially identical in structure and operation. However, they may be adjusted to operate effectively at difierent temperatures and each may be provided with a bellows I9 mounted on the base and operatively engaging a lever pivoted at 8| and normally retained under tension against the bellows by means of a spring 82. Adjustable stops 83 and 84 are provided to limit the movement of the lever in a predetermined range. These stops may be eccentrics mounted on suitable bolts or screws whereby they may be secured in adjusted position. A threaded screw 85 is mounted in the upper base 86 of the thermostat and engages the end of the push rod I2 so that rotating this screw 85 is equivalent to lengthening or shortening the push rod I2, thereby varying the setting of the thermostat. The screw 85 is provided with an arm 81 secured thereto and adjustably connected to the lever 80 by means of a link 88. A dial 89 is secured to the screw 85 in a manner to be rotated therewith, and is provided with an indicator or dial for indicating the setting of the thermostat. For instance, the thermostat may normally be set to start to open the vent I8 at 75". However variations in the outdoor temperature will cause the combined operation of the thermostats 65 and 66 to control their associated vents so that pressure may be admitted to the bellows through the conduit 61 and thereby vary the effective operating temperature of the room thermostats, and the new setting will be indicated by the dial 89.

Each room thermostat will normally control its respective heat exchanger to maintain the room at the temperature to which the thermostat is manually adjusted, for example 75. The outdoor thermostat 65 is for the purpose of varying the normal setting of the room thermostats when required during the summer when he outdoor and' temperature rises above 75, For instance, the thermostat 65 may be adjusted to start to close its associated vent 10 at 75 and to complete the closing of the vent at Therefore, there will be a gradual increase in the setting of the indoor thermostat between the outdoor temperatures of 75 and 105. As the temperature outside drops, the vent 'II] will open and will remain completely open at all temperatures below 75.

The thermostat 66, which is in air controlling series with thermostat 65, is a low temperature control to increase the setting of the room thermostats during winter when extremely low temperatures prevail, and the vent of thermostat 65 is open. For instance, the thermostat 66 may be adjusted to start to close at about 10 and be completely closed at' 20. Therefore, during summer, the thermostat 65 will be the master thermostat for controlling the setting of the room thermostats, while in winter the thermostat 66 operates as a master thermostat for the same purpose.

It will therefore be apparent that when extremely high outdoor temperatures prevail, the thermostat 65 will control the indoor thermostats to vary the setting in accordance with variations in outdoor temperature above a predetermined minimum, and the range of variation may be limited by means of the adjustable stops 83 and 84 for the lever 80. Also during the winter,

when extremely cold outdoor temperatures prevail, the thermostat 66 becomes the master thermostat, and will vary the setting of the room thermostats at all points within a temperature range below a predetermined maximum.

It will be understood, of course, that in some installations it may be desirable to omit the outdoor thermostats 65 and 66, and the associated means for varying the setting of the thermostats I. Also either one of the thermostats 65 and 66 may be omitted, and the other thermostat installed to vary the setting of the thermostats I in accordance with variations in either high or low outdoor temperatures as desired. The thermostat I9 and the associated pneumatic control for the winter and summer valve 8, may also be omitted in some installations, if desired, and the valve 8 may then be controlled manually or in any other suitable manner. If one or more of the above noted controls are omitted from the installation, the control of the heating and cool ing mediums will be accomplished in the same manner as previously described, but only in accordance with variations in room temperature, and in accordance with the position of the winter and summer control valve 8.

The operation of the room thermostat is not changed with respect to temperature when the valve 8 is moved either manually or otherwise from summer control of a cooling medium to winter control of a heating medium, or vice versa. In any event the room thermostats always operate in the same manner with respect to temperature. The vent I8 always opens gradually in either winter or summer in response to a drop in temperature and closes in response to an increase in temperature. However in winter, when a heating mediumi 4used, the pressure in conduit I0 is gradually i creased as the vent closes to When the thermostats 65 and 66 and associated parts used to vary the setting of the room thermostat are omitted, it is sometimes desirable to maintain the normal setting of the room thermostat during winter or low outdoor temperatures, and to increase this setting during summer control, or when high outdoor temperatures prevail. Fig. 5 illustrates an embodiment of the invention arranged to accomplish this result.

The thermostat illustrated in Fig. 5 is similar to the room thermostat previously described and illustrated. in Fig. 3, and the pressure conduits are connected thereto in the same manner. However, the base of the thermostat is provided with a chamber 90 in which a flexible diaphragm 9! is secured by means of a threaded plug 92 having a suitable vent therethrough. A spring 93 is protill Elli

dill

iid

vided for normally maintaining the diaphragm in the raised position illustrated. An adjustable stop is arranged to limit the downward movement of the diaphragm and may comprise a screw or other adjustable member 94. A lever 95 is pivoted at 96 to the valve post Ma. and is connected to the diaphragm 9| by means of a suitable link 97. The opening 90 through which the link 91 passes in the base is sufiiciently large to permit air pressure in the thermostat chamber III) to be applied to the diaphragm, and move the diaphra'gm downwardly against the limiting stop 94.

retain it open. The pressure to be applied may.

be predetermined by adjusting the diaphragm stop EM.

As previously stated the lever We is fulcrumed by the spring IS, the normal fulcrum being substantially at a point indicated by the reference character F. Inthe embodiment illustrated in Fig. 5, the lever I5a is also caused to partially fulcrum at the point indicated by the reference character Gr when pressure is applied within the thermostat chamber for summer control.

The operation of the thermostat is as follows:

control, the conduit 6 leading to the thermostat chamber lib is connected to the exhaust port 9, and therefore there is no appreciable pressure in the chamber and the mechanism just described performs no functidn as the spring 99 does not engage the lever l5a. When the valve 9 is in a position for summer control and pressure is admitted into the chamber l lb, the resilient spring finger 99 will apply a predetermined yielding pressure to the valve lever I50. and tend to open the vent I90. and to delay the closing thereof in response to high temperature. In this construetion, while the limits of the vent opening-andclosing temperature range may relatively be substantially the same in either winter or summer,-

the range will automatically be raised in summer to cause effective operation at higher tempera: tures in accordance with the adjustment of the diaphragm limiting stop 94. In this embodiment the variation in setting of the thermostat is automatically controlled by moving the valve 8 from winter to summer control or vice versa, while tion ll having an inlet I02 and an outlet I03.

An adjustable valve member I04 is threaded into the body portion IM and provided with a tapered reduced portion I arranged to engage a seat I06. It is desirable that a minimum passage be provided whereby the inlet I02 may always deliver a predetermined minimum air flow. to the outlet I03 when the valve is closed. A restricted passage i0! is provided in the tapered portion I I15. The size of the passage may be predetermined to provide constant minimum air flow when the tapered portion of the valve member I04 is snugly seated. The valve member I04 may, however, be adjusted to increase the flow if desired, and may be entirely removed for cleaning or repairing when desired. A suitable filter I08 may be provided in the inlet.

Fig. '7 illustrates a single thermostat for controlling the pneumatic setting adjustment of the room thermostats. This single thermostat may be substituted for the thermostats 65 and 66 i1- lustrated in Fig. 1. In this embodiment, the thermostat 6511 may be substantially identical with the thermostat 65 previously described, with the addition of various elements for controlling the secondary vent 15a. In order to control this vent by means of the same thermostat mechanism which controls the vent la, the thermostatic push and pull rod I09 is threaded at H0 and provided with an adjusting nut Ill arranged to bear against a valve lever H2 pivoted at M3. It will be apparent that the temperature control of the lever Ha controlling the vent 10a may be adjusted by means of the adjusting nut 10a, where by the vent 10a will be opened and closed at predetermined high temperatures. The vent. a may also be controlled to open and close at predetermined low temperatures by adjustment of the nut iii, the position of which controls the movement of the valve lever H2. The vents 10a. and 150. may thereby be controlled in substantially the same manner with respect to temperature as in the structure illustrated in Fig. i

When the valve 8 is moyed to a position for winter f wherein the two thermostats 05 and 69 are used.

It will be apparent to those skilled in the art that various changes in detail may be made without departing from the spirit of the invention. It is therefore desired that the invention be limited only by the prior art and the scope of the appended claims.

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is: I

1. In a temperature control system, means for regulating the flow of heat exchanging medium, a thermostat for controlling said regulating means in response to room temperature, pneumatically controlled means to vary the setting of saidthermostat and comprising a conduit for supplying pneumatic power, thermostatic mechanism effective above a predetermined high tem-'.

sive means for controlling said ports relative to predetermined high and low temperatures.

2. In a temperature control system, means for regulating the flow of heat exchanging medium,

a thermostat for controlling said regulating means in response to room temperature, pneumatically controlled means to vary the setting of said thermostat and comprising a conduit for supplying pneumatic power, thermostatic mechanism effective above a predetermined high temperature and below a predetermined low temperature to vary the setting of said room thermostat, said mechanism comprising two leak ports in series for controlling the transmission of power in said conduit, and temperature responsive means for controlling one of said ports and maintaining the other port open when high outdoor temperatures prevail and reversing the control of said ports when low temperatures prevail.

3. A temperature control system comprising a pneumatically controlled regulating means for controlling the flow of heat exchanging medium to a heat exchanger, a summer conduit and a winter conduit for selectively transmitting pneumatic power to actuate said regulating means, means to select a desired conduit, a thermostatically controlled throttle valve mechanism for one selected conduit and arranged to vent the other selected conduit, and means controlled by the pneumatic power in one of said conduits to supply a cooling medium when the summer conduit is selected and a heating medium when the winter conduit is selected.

4. A temperature control system comprising a heat exchanger, pneumatically operable regulating means for controlling the flow of heat eX- changing medium to said heat exchanger, a summer conduit and a winter conduit for selectively transmitting pneumatic power to actuate said regulating means, temperature controlled means for selecting a desired conduit in accordance with seasonal requirements, a throttle valve for one selected conduit and arranged to vent the other selected conduit, a non-reversing thermostat for operating said valve in accordance with room temperature requirements, temperature responsive means to vary the setting of said valve thermostat relative to predetermined temperature variations, and automatically controlled means to supply a cooling medium when said summer conduit is selected and a heating medium when said winter conduit is selected.

5. In a system of the class described, in combination, condition changing means, means for supplying medium to said condition changing means, pressure actuated regulator means for controlling the supply of said medium, a controller responsive to a condition which said condition changer is controlled in accordance with for controlling said regulator means, a first path for supplying fluid under pressure to said regulator means, said first path being connected to said controller in a manner to cause the pressureof said fluid to increase with increase in value of said condition, a second path for supplying fluid under pressure to said regulator means, said second path being connected to said controller in a manner to cause the pressure to be decreased upon increase in value 011 said condition, selective means for rendering only one path or the other operative to thereby reverse the action of said controller upon said regulator means, and means controlled by said selective means tor changing the type of medium supplied to said condition changing means.

6. In a system of the class described, in combination, condition changing means, means for supplying medium to said condition changing means, pressure actuated regulator means for controlling the supply of said medium, acontroller including a single valve device and a condition responsive device for actuating said single valve device, a first path for controlling the application of pressure fluid to said regulator means, said first path being connected to said valve device in a manner to cause the flow of medium to said condition changing means to be increased as the value of said condition increases, a second path for controlling the application of pressure fluid to said regulator means, said second path also being connected to said single valve device and in a manner to cause the flow of medium to said condition changing means to be increased as the value of said condition decreases, and selective means to render only one path or the other operative, to thereby reverse the action of said valve device on said regulator means.

'7. The combination of regulating means for controlling the flow of conditioning medium, pressure responsive actuating means for actuating said regulating means, a first conduit and a second conduit for selectively directing fluid under pressure to said actuating means, a condition responsive valve means always operating in the same manner with respect to the condition to which it responds, means for directing said fluid to a desired conduit in accordance with control requirements, one of said conduits being arranged to direct said fluid directly through said valve means to said actuating means whereby the normal operation of said valve means provides a pressure controlling throttle in said conduit, the other conduit being arranged to direct power directly to said actuating means whereby the normal operation of said valve means provides a pressure relieving vent from said conduit.

8. The combination of regulating means for controlling the flow of heat exchanging medium, pneumatic means for actuating said regulating means, a winter conduit and a summer conduit for selectively directing pneumatic power to control said actuating means, a thermostatic valve means operatingalways in the same manner with respect to temperature, means for selecting a desired conduit in accordance with temperature control requirements, one of said conduits being arranged to direct power directly through said thermostatic valve means to said actuating means whereby the normal operation of said thermostatic valve means provides a pressure controlling throttle in said conduit, the other conduit being arranged to direct power directly to said actuating means wherebythe normal operation of said thermostatic valve means provides a pressure relieving vent from said conduit, and means for varying the control point of said thermostatic valve means in a manner to maintain a higher temperature during the summer than during the winter.

9. The combination of regulating means for controlling the flow of heat exchanging medium, pneumatic means for actuating said regulating means, a winter conduit and a summer conduit for selectively directing pneumatic power to control said actuating means, a thermostatic valve means operating always in the same manner with respect to temperature, means for selecting a desired conduit in accordance with temperature control requirements, one of said conduits being arranged to direct power directly through said thermostatic valve means to said actuating means whereby the normal operation of said themostatic valve means provides a pressure controlling throttle in said conduit, the other conduit being arranged to direct power directly to said actuating means whereby the normal operation of said thermostatic valve means provides a pressure relieving vent from said conduit, and means responsive to outdoor temperature for adjusting said thermostatic valve means in a manner to maintain a relatively low temperature when outside temperature is low, while'raising the temperature maintained as outside temperature increases.

10. The combination of regulating means for controlling the flow of heat exchanging medium, pneumatic means for actuating said regulating means, a winter conduit and a summer conduit for selectively directing pneumatic power to control said actuating means, a thermostatic valve means operating always in the same manner with respect to temperature, means for selecting a desired conduit in accordance with temperature control requirements, one of said conduits being arranged to direct power directly through said thermostatic valve means to said actuating means whereby the normal operation of said thermostatic valve means provides a pressure controlling throttle in said conduit, the other conduit being arranged to direct power directly to said actuating means whereby the normal operation of said thermostatic valve means provides a pressure relieving vent from said conduit, and means controlled inaccordance with the selection of said conduits for adjusting said thermostatic valve means in a manner to maintain a higher space temperature when the summer conduit is selected than when'the winter conduit is selected.

11. In a system of the class described, in combination, condition changing means, means for supplying medium to said condition changing means, pressure actuated regulator means for controlling the supply of said medium, a controller responsive to a condition in accordance with which said condition changer is controlled for controlling said regulator means, a first path for supplying fluid under pressure to said regulator means, said first path being connected to said controller in a manner to cause the flow of medium to said condition changing means to be increased as the value of said condition increases;

said condition changer when one of said paths is selected than when the other of' said paths is selected. I

12. In a heating and cooling system, in combination, heating means for heating a space,

cooling means for cooling said space, a thermostat influenced by the temperature in said space for controlling both said heating means and said cooling means, a pressure actuated device for adjusting said thermostat, thermostatic means responsive to outside atmospheric temperature, and valve means for controlling the pressure applied to said pressure actuated device, said valve means being controlled by said thermostatic means in a manner to raise the control point of said thermostat when outside temperature either rises above a predetermined higher value or falls below a predetermined lower value.

13. In a heating and cooling system, in combination, heating means for heating a space, cooling means for cooling said space, a thermostat influenced by the temperature in said space for controlling both said heating means and said cooling means, a pressure actuated device for adjusting said thermostat, a plurality of thermostats influenced by outside atmospheric temperature, and means controlled by the cooperative action of said plurality of outside temperature influenced thermostats for controlling the presmostats acting to vary the pressure applied to said pressure actuated device in a manner to raise the control point of said space temperature influenced thermostat when outside temperature falls below a predetermined lower value and another of said outside temperature influenced thermostats acting to vary the pressure applied to said pressure actuated device in a manner to raise the control point of said space temperature influenced thermostat when outside temperature rises above a predetermined higher value.

15. In a summer-winter control system, in combination, heating and cooling means for heating or cooling a space, control means for said heating and cooling means comprising a single pressure actuated motor, said motor controlling heating medium in Winter and controlling cooling medium in summer, a single valve device for controlling'the supply and exhaust of air to said pressure actuated motor, an operating member for said valve device, said operating member being associated with said valve device at all times in a manner to cause movement of said operating member in one direction to have the same effect upon said valve device, a single thermostatic element responsive to space temperature for actuating said operating member in one direction or the other in response 'to changes in space temperature to thereby increase or decrease the pressure applied to said pressure actuated motor in accordance with variations in space temperature, reversing means for reversing the direction of change in pressure caused by a given change in temperature at said thermostatic element, adjusting means for adjusting the thermostatic element in a manner to vary the space temperature maintained, pressure actuated means for controlling said reversing means and said adjusting means, and means remote from said thermostatic element for controlling pressure applied to said pressure actuated means.

16. In a temperature control system, in com-"- controlled motor for operating said regulating means, a thermostatic valve mechanism for controlling the application of fluid pressure to said motor, two paths for transmitting fluid pressure to said motor under the control of said thermostatic valve mechanism, said paths providing for reversing the control action of said thermostatic valve mechanism, a fluid pressure operated resilient means operating on said thermostatic valve mechanism for varying the control point thereof, and means operable from a remote point for varying the fluid pressure applied to said pressure operated resilient means.

JOHN M. LARSON. 

